Compton Profile Study and Electron Momentum Density Reconstruction in Hexagonal Mg

Special directions in momentum space. III. Practical applications

“…Compton (Cooper, 1985;Cooper et al, 2004), neutron scattering (Reiter, Mayers & Noreland, 2002;Reiter, Mayers & Platzman, 2002) or ACAR (West, 1995;Hautojä rvi, 1979;Haynes et al, 2012;Dugdale, 2014)], that allow for reconstructing (p) with the highest efficiency. Here, an exception is the maximum entropy reconstruction method (Dobrzyń ski & Holas, 1996;Fornalski et al, 2010;Brancewicz et al, 2013).…”

Electron momentum density of hexagonal Zn studied by high-resolution Compton scattering

“…In order to get the CPs, the measured spectra were corrected for background scattering, absorption of photons in the sample, detector efficiencies, scattering cross section and multiple-scattering contribution (MSC) (Brancewicz et al, 2013). The spectrum of multiple-scattered X-rays was simulated by the Monte Carlo method with the use of the MUSCAT program (Brancewicz et al, 2016), which takes into account the exact experimental geometry [up to triple scattering in the sample ( The first Brillouin zone for the hcp structure, marked with high-symmetry points (blue dots) that define the five directions in reciprocal space chosen for the CP measurements.…”

“…Subtraction of two directional CPs, measured at two specific crystallographic directions, removes all isotropic components from the CPs (i.e. core electrons and background contributions) and forms the so-called difference profiles (anisotropies), which reveal the anisotropy of the electron momentum density distribution associated with the crystal symmetry and the shape of the Fermi surface (fermiology) of the studied material (Sakurai et al, 1995;Hä mä lä inen et al, 1996;Dugdale et al, 2000;Reniewicz et al, 2001;Mizusaki et al, 2003;Bellin et al, 2004;Dugdale et al, 2006;Brancewicz et al, 2007;Huotari et al, 2007;Choudhary et al, 2011;Brancewicz et al, 2013;Sharma et al, 2015).…”

“…Following this idea, the need for high-resolution and high experimental statistics Compton scattering measurements for hexagonal metals (Mg, Zn, Cd) with the use of synchrotron radiation was suggested by Brancewicz et al (2007). This kind of experiment was successfully carried out for a magnesium single crystal with the lowest atomic number among those three metals (Brancewicz et al, 2013). The good quality of the four measured directional CPs allowed for a quantitative discussion of data agreement with theoretical calculations, even in the region of low electron momenta, and successful reconstruction of the 3D electron momentum density using the maximum entropy method (MEM).…”

A Monte Carlo study of high-energy photon transport in matter: application for multiple scattering investigation in Compton spectroscopy

“…Extraction of the Compton profile from experimental spectra is a standard procedure including a series of energy-and geometry-dependent corrections. However, there are still small but significant discrepancies observed between theoretical and experimental Compton profiles even in highmomentum regions, where theoretical description of core electrons should work well (Brancewicz et al, 2013). There are two possible sources of this discrepancy: one is the uncertainty associated with the experimental background measurements and the other is the influence of multiple-scattered photons (MSC) in experimental spectra.…”